The present invention relates to large forging presses and more particularly to a clearance holes arrangement for a crosshead assembly which is part of a frame structure for the forging press.
The present application is closely related to the subject matter described in patent application U.S. Ser. No. 821,790 entitled "FORGING PRESS WITH ADJUSTABLE DAY-LIGHT AND WITH YOKE DESIGN FOR ATTACHING TIE-RODS TO CROSSHEADS" which is commonly assigned with the present application.
As is known and by way of background, forging presses are used for shaping metal slabs or ingots into and products of desired shape by pressing the metal slab between a pair of dies to give it its shape.
Structurally, the forging press includes a very large steel frame which surrounds a stationary bridge or platform on which a workpiece is placed. In a particular type of forging press known as a pull-down press the frame is movable up and down relative to the stationary bridge. The frame is rectangularly shaped and as large as a high rise building. The horizontally extending members of the frame include an upper crosshead which extends transversely to the stationary bridge and a lower crosshead extending below the bridge and coextensively with the upper crosshead assembly. Vertically extending tie-rod assemblies on either side of the bridge connect the upper crosshead and the lower crosshead to one another to complete the frame. The upper crosshead of the frame is used for squeezing a workpiece between the frame and the stationary bridge. Very power hydraulic jacks located on the lower crosshead and braced against the bottom of the bridge are operable to push the lower crosshead assembly downwardly and thereby produce enormous compressive forces on the workpiece which is placed on the upper surface of the stationary bridge, directly below the upper crosshead.
Each one of the crosshead assemblies consists of several horizontally spaced sections each of which includes a number of vertically oriented plates which are tied together across their thickness to form single units or subassemblies.
The plates of any given subassembly are held together. and reinforced by several rows of horizontally arranged ties which pass through appropriate holes in the plates. Ties can be withdrawn from the unobstructed outermost subassemblies without hindrance to permit dismantling or servicing of those crosshead subassemblies.
However, the ties which hold together intermediate sections of a crosshead assembly cannot be withdrawn unless the outer sections of the crosshead assembly are dismantled first. This is quite disadvantageous because servicing or repair of intermediate crosshead subassemblies is required at times and dismantling of the outer subassemblies for this purpose is very costly, timewise and monetarily. Each crosshead plate weighs several tons and several days may be lost due to this extra unnecessary task.